The present invention is in the field of binuclear non-heme iron compounds. In particular, the invention relates to binuclear iron compounds which are useful as catalysts in the oxidation of various organic substances, such as alkanes, arenes, olefins and sulfides. The invention further relates to a method for preparing alcohols from alkanes, or arenes, epoxides from olefins, ketones from alkanes, sulfoxides and sulfones from sulfides using the binuclear iron compounds.
As known petroleum reserves are rapidly depleted, a need exists to secure an alternative source of industrial chemical feedstocks now derived from oil. One approach is to convert relatively abundant coal and natural gases such as methane into synthesis gas, a mixture of carbon monoxide and hydrogen, which can then be transformed into alcohols, acids, esters, etc. Accordingly, the need remains to provide efficient methods to convert hydrocarbons directly into oxidized organics.
Binuclear non-heme iron centers such as those found in the active site of methane monooxygenase (MMO) act as oxygen atom transfer catalysts by a complex, poorly understood mechanism.1,2 Despite advances in understanding the structural,3 spectroscopic,4,5 and mechanistic aspects of enzymatic alkane oxidation,4,5 attempts to effect hydrocarbon oxidation by a biomimetic mechanism have not succeeded.1,2 While synthetic non-heme diferric systems are reported to oxygenate substrates in the presence of either dioxygen6 or alkyl peroxides,1,2,4,5,7-13 the peroxide chemistry is now thought to be dominated by oxygen-based free radical pathways.14-17 
The present invention provides a catalytically competent binuclear non-heme Fe complexes that can perform biologically relevant oxo-atom transfer chemistry.18,19 Specifically, the invention provides compounds of the formula [Fe22+(H2Hbamb)2(N-MeIm)2], 1, [Fe2+, Fe2+], Scheme 1),20a as well as its mixed-valence [Fe2+, Fe3+], 2, and diferric [Fe3+, Fe3+], 3, core states, all of which possess remarkable reactivity properties. Thus, both the [Fe2+, Fe2+, 1, and [Fe2+, Fe3+], 2, complexes are uniquely capable of catalyzing the oxidation of alkanes, alkenes and sulfides by the known oxygen atom donor, iodosylbenzene (OIPh). The catalytic chemistry of non-heme 1 and 2 parallel that reported for cytochrome P-450, a system believed to involve a porphyrin cation radical (Fe4+xe2x95x90O] reactive intermediate.21-23 
Accordingly, one object of the present invention is to provide a binuclear metal complex having the structure: 
wherein M1 and M2 are independently selected from the group consisting of Fe, Co, Mn and Ru; wherein m and n are independently +2 or +3; wherein R1, R2, R3, R4, R5 and R6 independently a linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C1-C6 alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate.
Another object of the present invention is to provide a ligand having the structure: 
wherein R1, R2, R3, R4, R5 and R6 are independently and optionally substituted linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C1-C6 alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate.
A further object of the invention is to provide a method of preparing an alcohol from an alkane or cycloalkane wherein said alkane or cycloalkane is optionally substituted by an aryl, which comprises:
(A) dissolving the alkane or cycloalkane in a suitable solvent to form a solution; and
(B) treating the solution with an oxygen atom donor in the presence of a binuclear metal complex having the structure: 
xe2x80x83wherein M1 and M2 are independently selected from the group consisting of Fe , Co, Mn and Ru; wherein m and n are independently +2 or +3; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C1-C6 alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate, under suitable conditions to form the alcohol.
A further object is to provide a method of preparing an epoxide from an alkene or cycloalkene, wherein the alkene or cycloalkane is optionally mono-, di-, tri- or tetrasubstituted independently with an optionally substituted linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl, which comprises:
(A) dissolving the alkene or cycloalkene in a suitable solvent to form a solution; and
(B) treating the solution with an oxygen atom donor in the presence of a binuclear metal complex having the structure: 
xe2x80x83wherein M1 and M2 are independently selected from the group consisting of Fe , Co, Mn and Ru; wherein m+n is +4 or +5; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; where in Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C1-C6 alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate, under suitable conditions to form the epoxide.
An additional object is to provide a method of preparing a sulfoxide from a dialkyl sulfide, alkyl aryl sulfide or diaryl sulfide wherein each alkyl is independently an optionally substituted C1-C6 alkyl, C3-C9 alkylalkenyl, or C5-C6 cycloalkyl, or the sulfide S atom interrupts an optionally substituted C5-C10 alkane ring, which comprises:
(A) dissolving the sulfide in a suitable solvent to form a solution; and
(B) treating the solution with an oxygen atom donor in the presence of a binuclear metal complex having the structure: 
xe2x80x83wherein M1 and M2 are independently selected from the group consisting of Fe, Co, Mn and Ru; wherein m+n is +4 or +5; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein is 1 or 2, and q is 0, 1 or 2 such that m+n xe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C1-C6 alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate, under suitable conditions to form the sulfoxide.
Another object of the invention is to provide a method of preparing an arene alcohol from an arene wherein said arene is optionally substituted by an aryl, which comprises:
(A) dissolving the arene in a suitable solvent to form a solution; and
(B) treating the solution with an oxygen atom donor in the presence of a binuclear metal complex having the structure: 
xe2x80x83wherein M1 and M2 are independently selected from the group consisting of Fe, Co, Mn and Ru; wherein m and n are independently +2 or +3; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C1-C6 alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate, under suitable conditions to form the arene alcohol.
Another object of the invention is to provide a method of preparing a sulfone from a dialkyl sulfide, alkyl aryl sulfide or diaryl sulfide wherein each alkyl is independently an optionally substituted C1-C6 alkyl, C3-C9 alkylalkenyl, or C5-C6 cycloalkyl, or the sulfide S atom interrupts an optionally substituted C5-C10 alkane ring, which comprises:
(A) dissolving the sulfide in a suitable solvent to form a solution; and
(B) treating the solution with an oxygen atom donor in the presence of a binuclear metal complex having the structure: 
xe2x80x83wherein M1 and M2 are independently selected from the group consisting of Fe, Co, Mn and Ru; wherein m+n is +4; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein R1, R2, R3, R4, R5 and R6 are independently an optionally substituted linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i,j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole, and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate, under suitable conditions to form the sulfone.
Another object is to provide a method of preparing a alcohol from an alkene or cycloalkene wherein said alkene or cycloalkene is optionally mono-, di- or trisubstituted independently with an optionally substituted linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl, which comprises:
(A) dissolving the alkene or cycloalkene in a suitable solvent to form a solution; and
(B) treating the solution with an oxygen atom donor in the presence of a binuclear metal complex having the structure: 
xe2x80x83wherein M1 and M2 are independently selected from the group consisting of Fe, Co, Mn and Ru; wherein m+n is 4 or 5; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C1-C6 alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate, under suitable conditions to form the alcohol.
Another object is to provide a method of preparing a ketone from an alkene or cycloalkene wherein said alkene or cycloalkene is optionally mono-, di- or trisubstituted independently with an optionally substituted linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl, which comprises:
(A) dissolving the alkene or cycloalkene in a suitable solvent to form a solution; and
(B) treating the solution with an oxygen atom donor in the presence of a binuclear metal complex having the structure: 
xe2x80x83wherein M1 and M2 are independently selected from the group consisting of Fe, Co, Mn and Ru; wherein m+n is 4 or 5; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C1-C6 alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate, under suitable conditions to form the ketone.
A final object of the invention is to provide a method of preparing a binuclear metal complex having the structure: 
wherein M1 and M2 are independently selected from the group consisting of Fe, Co, Mn and Ru; wherein m and n are independently 2 or 3; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein R1, R2, R3, R4, R5 and R6 are independently a linear C1-C6 alkyl, C5-C6 cycloalkyl or phenyl optionally substituted by a linear or branched chain alkyl, alkoxy, alkoxycarbonyl, carboxamido, or halogen; wherein (i) R1 and R2, (ii) R3 and R4, or (iii) R5 and R6 independently and optionally are linked covalently and together with the respective adjoining C atom comprise a spirocylic ring; wherein i, j and k are integers such that 2xe2x89xa6i+j+kxe2x89xa64; wherein p is 1 or 2, and q is 0, 1 or 2 such that m+nxe2x88x924=pxc3x97q; wherein (i) R1 or R2 and R3 or R4, (ii) R3 or R4 and R4 or R5, or (iii) R1 or R2 and R5 or R6 independently and optionally are linked covalently and together with the respective adjoining C atoms comprise a fused ring; wherein Ar is 1,2-phenylene, 1,2- or 2,3-naphthylene or 1,2- or 2,3-anthracenylene, wherein said Ar is optionally substituted by C1-C6 alkyl or alkoxy; wherein L is N-methylimidazole, N-ethylimidazole, N-1-propylimidazole or N-phenylimidazole; and wherein X is fluorine, chlorine, bromine, iodine, borate, tetrafluoroborate, sulfate, hydrogen sulfate, carbonate, hydrogen carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, perchlorate, nitrate, triflate, p-tosylate, mesylate, formate, acetate, tartrate or citrate, which comprises:
(A) preparing a dilithio, disodio or dipotassio salt of a ligand having the structure: 
xe2x80x83wherein R1, R2, R3, R4, R5, R6, i, j, k and Ar are defined as above; and
(B) contacting the salt formed in step (A) with an approximately equal amount of {M1m/M2n}(L)2(Xxe2x88x92p)q(S)2 wherein M1, M2,, L and X are defined as above; wherein m and n are each +2; and pxc3x97q=m or n; wherein S is a solvent selected from the group consisting of a linear or branched alkyl alcohol and water; under suitable conditions to form the binuclear metal complex.